Cosmetic applicator brushes, and in particular mascara applicator brushes are typically twisted wire brushes. During manufacturing, a multiplicity of fibers is retained between two sides of a stem pin that has been bent and folded back on itself. Once the multiplicity of fibers is in place, the stem pin is then twisted. The twisting of the stem pin causes the multiplicity of fibers to become helicoidally distributed into helicoidal fiber arrays. Typically, in a standard mascara applicator brush, the distance between corresponding points on adjacent fiber arrays, also known as the pitch, is fixed along the length of the brush.
The pitch between adjacent fiber arrays in the assembled brush defines a fiber distribution array. The fiber distribution array affects the amount of mascara that can be loaded onto the brush, and therefore mascara application (both in amount and distribution) is affected. A more tightly twisted brush tends to load less mascara than a brush that is not as tightly twisted. Due to the fact that the pitch between adjacent fiber arrays in standard, assembled cosmetic applicator brushes is fixed along the entire length of the assembled brush, the amount of product loaded by the brush is substantially the same. As a result, the amount of mascara that can be applied by various regions of the brush cannot readily be varied.